206 
part. The arm-spines are slender and smooth; 1. joint has 4 spines, 
2.—3. joint has 5—6 spines, gradually increasing in length from 
below, the upper ones 1!/x times as long as the corresponding 
arm joint; they join in the middle line on the dorsal side (Pl. II. 
Fig. 5). The 4th joint has 4 spines, which do not join on the 
dorsal side, the longest (upper) being scarcely as- long as the joint. 
The following joints have three and then two short spines, placed 
; far down on the side -of the joint (Fig 2). The 
j inner tentacle pore is small, but distinet, carrying 
a peculiar Ccurved tentacle scale at its outer - edge 
(Pl. II. Figs. 1, 10). The following pores are very 
small, covered by' the single tentacle scale, which is 
elongate and has quite the appearance of being the 
first (lower) arm spine. 
It seems beyond doubt that the animals are 
fullgrown in spite of their small size. Among the 
rather numerous specimens there are none which 
surpass 2 mm. in diameter of disk; however, most 
of them contain ripe sexual products. These facts 
Fig. 2. naturally lead to the conclusion that the specimens 
A pair of the KE hest 
outer arm- are fullgrown. This is then one of the smalles 
joints of Miero- 
yåsura: from Ophiurids. made known as yet—if not the smallest. 
theventral side. Tt is true that the Ophiophthirius aetinometræ des- 
"vertebræ are cribed by Dåderlein?) is still smaller, having a 
seen through  . ' 3 
the side-plates, diameter of disk of only 0.8 mm.; but there is 10 
Shy, proof that the specimens 'examined were fullgrown, 
and Dåderlein also ns, that they possibly are only young 
stages. 
Regarding the inner anatomy of the animal I would point out 
that there is only a single pair of comparatively large genital 
Oorgans in each interradial space. Bursæ are wholly wanting; 
the genital products therefore must probably be 'delivered through 
i 3 Uber einige epizoisch lebende Ophiuriden. In Semon's FPolsebuage 
reisen. V. Jen. Denkschr. VIII. 1898 p. 486. 
